An aircraft or an airplane must be capable of promptly recovering from a stall at any angle of attack (AOA) that the airplane can achieve at any permissible power setting. This is required from a regulatory standpoint as specified in 14 CFR § 25.145. Additional requirements and design guidelines applicable to this flight regime may be imposed by an airplane manufacturer. Providing sufficient recovery capability at this condition has traditionally resulted in airplane design compromises affecting cost, complexity, and performance.
Existing methods to provide sufficient recovery capability traditionally manage pitch-up and ensure prompt nose-down recovery from high AOA by applying constraints and modifications to the wing leading edge and trailing edge flap designs to reduce a magnitude of aerodynamic pitch-up; use of stall strips and other flow control devices on the wing leading edge to manage a progression of airflow separation; applying constraints and modifications to a wing anti-ice protection system to reduce a magnitude of aerodynamic pitch-up in icing conditions; and adding area to a horizontal tail to increase stability and pitch control power.
Existing methods impact system complexity, weight, maintenance, and cost. Furthermore, these solutions can negatively impact airplane performance by increasing operational speeds such as a landing approach speed affecting customer performance guarantees and sales.
What is needed is a system to ensure prompt nose-down recovery of the aircraft at critical conditions without having to add complexity to the aircraft design, increase weight, and/or increases costs.